You can sue anybody for anything, but I doubt you would win. Firstly, why did you need the root canal in the first place? Likely the tooth was either compromised by an impact injury or have enough decay that the pulp was infected, which means there was not really much natural tooth...
The problem isn't the material but rather the dentist and the lab. The single front tooth is always difficult. I have my labtech come in and custom color crowns in the office.The tooth looks grey which needs blocking, this can be done with opaque cements when using translucent...
Sounds like the teeth were not properly prepared for a porcelain to metal crown. The exposed metal is not acceptable. It will likely wear through rather quickly which calls for a new crown. I would ask the dentist to re-make them after the teeth are properly trimmed enough for...
